- Grid tie PV panel installation
- Grid tie inverter
- Transfer switch
- Protected loads/appliances
- Backup system batteries
- Backup system inverter
- Unsecured loads which require high power connection
- Export meter
- Normal meter
This is quite a complex system that combines the ability to sell electricity back to the grid via the export meter (8) with backup power should the grid fail. The electricity generated by standard grid tie photovoltaic systems designed to export power can't be used when there's a power cut. This is because they are designed to protect the grid from making it live when there's a problem or scheduled maintenance.
This system overcomes this problem by transferring the power produced by the solar panels to the secured backup side (4) The protected/secured side is fed power by a second, non grid tie inverter (6) that draws it's power from the batteries.
When the solar panel power is transferred to the secured side the grid tie inverter (2) thinks that the output from the backup inverter (6) is the grid and injects it's power into the secured side.
There's nothing more embarrassing than having 20K worth of solar panels on your roof and no power when there's a power cut and it's sunny!